Photophobia (from Greek φῶς — phōs, "light" and φόβος — phobos, "fear") /ˌfəʊtəʊˈfəʊbiə/ is a symptom of abnormal intolerance to visual perception of light. As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear of light such as heliophobia.
Patients may develop photophobia as a result of several different medical conditions, related to the eye or the nervous system. In some cases those who are born with it see the full spectrum of light. While in the direct sun light it causes red glare around the visual field which causes pounding headaches. Photophobia can be caused by an increased response to light starting at any step in the visual system, such as:
Too much light entering the eye. Too much light can enter the eye if it is damaged, such as with corneal abrasion and retinal damage, or if its pupil(s) is unable to normally constrict (seen with damage to the oculomotor nerve).
Due to albinism, the lack of pigment in the colored part of the eyes (irises) makes them somewhat translucent. This means that the irises can't completely block light from entering the eye.
The best treatment for light sensitivity is to address the underlying cause. Once the triggering factor is treated, photophobia disappears in many but not all cases.
Patients with photophobia will avert their eyes from direct light (sunlight and room lights), or may seek the shelter of a dark room or wear sunglasses.
A study by Stringham and Hammond, published in the Journal of Food Science, discusses the improvement in visual performance and decrease in light sensitivity (glare) in subjects taking 10 mg Lutein and 2 mg Zeaxanthin per day.
^Hazin R, Abuzetun JY, Daoud YJ, Abu-Khalaf MM (July 2009). "Ocular complications of cancer therapy: a primer for the ophthalmologist treating cancer patients". Curr Opin Ophthalmol20 (4): 308–17. doi:10.1097/ICU.0b013e32832c9007. PMID19491683.
^Fan X, Miles JH, Takahashi N, Yao G (November 2009). "Abnormal transient pupillary light reflex in individuals with autism spectrum disorders". J Autism Dev Disord39 (11): 1499–508. doi:10.1007/s10803-009-0767-7. PMID19499319.
^Sjaastad, Ottar; Bakketeig, Leiv S. (December 22, 2004). "Hangover headache: accompanying symptoms. Vågå study of headache epidemiology". The Journal of Headache and Pain (Springer Milan) 5 (4): 224–9. doi:10.1007/s10194-004-0130-5. ISSN1129-2369.